Experimental study of the effect of stress level on time dependent deformation of sandy clay soil

Abstract

Time-dependent deformation is important subject in geotechnical engineering where in long-term behavior is concerned. Time-dependent deformation is defined as development of shear-and/or volumetric deformation under a constant state of stress which can lead to long term settlement. In this paper, an experimental program is carried out to investigate the effects of stress levels on creep behavior of sandy clay soil. One-dimensional oedometer single stage and stepwise tests are carried out under single drainage condition on dried and water-saturated sandy clay soil at different stress levels, and the test results are explained using the coefficient of secondary compression (Cα) and compression index (Cc). In this study, it is assumed that the time-dependent deformation begins at the end of primary consolidation when the excess pore water pressure is completely dissipated. The experimental results indicate that at low stress level, large amount of time-dependent deformation is occurred in water saturated samples, and with increment of stress level, time-dependent deformation rate decreases, but in dry samples with increasing stress level time-dependent deformation rate increases. There is an approximately linear relation between the void ratio and the logarithm of effective axial stress, and the compression index (Cc) of the saturated sandy clay samples is higher than that of the dry sandy clay samples.